declare mySentence() to:
1) have return type void
2) receive a reference to a stringstream
3) have a local string variable called token
4) if you can extract a string from the stringstream into token
a) recursively call mySentence again passing it the
stringstream which is now advanced 1 word from where it was
b) output token after return from the recursive call
in main()
1) receive user input into a string
2) declare and initialize a stringstream with user input
3) call mySentence passing it the stringstream

Edit: Beaten by ArkM who is using similar logic. Here's the actual code I had written